Submitted to: AIPL Research Reports
Publication Type: Government Publication
Publication Acceptance Date: July 30, 2008
Publication Date: July 30, 2008
Citation: Norman, H.D., Hutchison, J.L., Wright, J.R. 2008. Sire conception rate: New national AI bull fertility evaluation. AIPL Research Reports. SRC1(7-08). Technical Abstract: Bull fertility evaluations called Estimated Relative Conception Rate (ERCR) were provided to the industry by Dairy Records Management Systems (DRMS) from 1986 to November 2005. In May 2006, AIPL assumed responsibility for evaluation of U.S. bull fertility. As an initial step, AIPL implemented the ERCR evaluation as previously computed by DRMS. Since 2006, the scope of the data was broadened from regional to national, and the model and edits were improved to increase reliability. Those efforts are ready for implementation for August 2008. The new evaluation will be called Sire Conception Rate (SCR) and will be based on conception rate rather than non-return rate. SCR will also utilize multiple services per lactation (up to 7), rather than first service only. Data will be primarily from 3 of the 4 major DRPCs, which is also an enhancement relative to previous evaluations. For the sake of improving reliability, the evaluation will also utilize what has been called an "expanded service sire term." This involves estimating components affecting bull fertility separately and then formulating the prediction as a sum of the components. In contrast to ERCR, SCR will be reported with one decimal. Evaluations will be expressed as deviations from the overall mean; an SCR of 1.2, for example, means that the bull is 1.2% above average, -1.2 would mean he is 1.2% below average, and 0.0 would mean he is average. All 6 traditional U.S. dairy breeds will be evaluated, provided sufficient data are available. To be publishable, a bull must have an AI status other than inactive and cannot be more than 13 years old. Holstein bulls must have at least 300 total breedings, 100 breedings in the most recent 12 months, and at least 10 herds. Minimum number of matings and herds are somewhat less for the other breeds, in order to allow for more publishable bulls.